We cannot buy a sense of perspective. It's hard to teach/learn perspective as well. And yet no matter what skills or tools you have or don't have, how you perceive those skills and tools will define how your process goes. If your perspective gets distorted then the sense of prioritization can get off track - tiny details take on tremendous (unworthy) weight. Or a certain part that took so many takes to get right feels essential to a mix even though it may best serve the song by being muted.  

This often happens with playing too, where musical athleticism (chops) can get confused with musicality. One contributes to the other, but achieving greater fluency with one does not guarantee the same fluency with the other. A sense of perspective must be continuously infused into the process of creating, recording, and mixing music. And it's so hard to do, to maneuver between various contexts while keeping a sense of perspective that may challenge what you already know or believe. 

Working solo, I try to come back to basic questions...What am I trying to communicate? What is the mood or tone of this piece? What is within my facility at this moment that will help me to meet those goals? When working with someone else, I try to set aside outside my own certainties so that I can better hear where he or she is coming from and pick up the thread from that point forward.